Electric furnace.



F. VON KTI GELGEN &: G. 0. SEWARD.

BLEGTRIG FURNACE.

APPLICATION FILED DEG.1B,1907.

Patented Dec. 13, 1910.

2 SHEETS-SHEET l WITNESSES:

Jgm/w F. VON KfiGELGEN & G. O. SEWARD. ELECTRIC FURNACE.

APPLICATION FILED DEG.18,1907.

978,171. Patented Dec.13,1910

2 SHEETS-SHEET 2.

FIG. 2.

iNVENTORS:

' FRANZ VON KttGELeEi OE HOLCOMBS ROCK, VIRGINIA, AN]: GEORGE O; sEwARn, OE

EAsT ORANGE, NEW JERSEY, ASSIGNOBS To VIRGINIA LABORATORY or NEW YORK, N. Y., A CORPO ATION or NEW YORK.

UNITED S TES ELECTRIC PATENT OFFICE rumr cE.

Application filed December s, 1907. Serial No. 407,019.

1 '0 all whom it may concern Be it known that we, FRANZ VON KfiGEL- GEN, a subject of the German Emperor, re-.

siding in Holcombs Rock, Bedford. county,

an electric furnace wherein the material under treatment shall be acted upon by radiated heat alone and without bringing it into contact with either the carbon electrodes or with the arc. For this purpose reverbera-- tory electric furnaces have been used wherein the are S rings between horizontally opposed penci s or electrodes entirely above the material under treatment,and a solid 1 cover is provided for reflecting the radiated heat downward against the material be 'neath. Such furnaces are impractical'by reason of the liability of the solid material or lining of the cover to be fused by the are and enter and contaminate the material under treatment.

Our invention provides'a reverberatory electric furnace which is free from liability of thus contaminating the material under treatment.

According to our invention we provide, in lieu of the approximately fiat or horizontal cover heretofore used, a hood whichlis mounted over the furnace chamber in which the arc plays, this hood being carried to such height that its inner surface or lining is so remotefrom the are as to be free from liability of being melted down by the heat therefrom. The deep hollow or cavity within the hood confines a body of approximately quiescent or stagnant air or other uses, which constitutesv a gaseous lining orsn'ield which serves the purpose of protecting the solid lining above from the extreme heat radiated upwardly from the arc, and appears to serve also 55s a mirror or reflector for directing downwardly a large propor- -tion of the heat rays.

that this form of cover has a reverberatory- Experience proves efficiency fully equal to that of a solid fiat cover. while, eing itself practically indestructible. e

Our invention will be best understood by reference to the accompanying drawing, wl1erein,-

Figure 1 is a vertical mid-section of a fur:

nace embodying our invention. Fig. 2 is 'a the carbon pencils.

Referring to the drawings, A -desi thereofforming-the arc chamber C, D D the carbon or graphite encils,.and E the hood. The parts A and may be construe-t plastic refracto filling or lining to a suitable thickness.

down into the base A, as shown, or be coneIectrOdes D' -D are best arran opposite openings in the b0 7 any suitable holders andadjustingm'eans for regulatirfifg the arc. Preferably a wateriacketed stu ng boir a surrounds each pen. oil in which water circulates, being introduced' through a pipe I; and discharged through a pi e 0-. Preferablvalso the lining .of the body ded in the lining, Zas best shown in Fig. 2. The details of COIl-SlIIlCfiOHOf these parts of thefurnace, however, form nopart of our the skill or .judgment'of the constructor or operator and according to the purpose for which the 'furnace is to'be used.

Ihe hood E is made of considerable height, its lower end being of such size and is molded a refractory lining which may be of lime, magnesia, or any other suitable material. The best shape for the innersurface Of'thelining is approximately a con'oid, as indicated approximately by the outline V0 in Fig. 1. A convenient way of constructing cone of approximately the shape shown in dotted lines at f; then to mold between this and the outer shell 9 the refractory lining J; then when this is solidified to place the hoodover the body and start the furnace so Patented Deena, 1910'.

horizontal section thereof in the plane of gnates the base of the'furnace, -B the central body,

he chamber C may extend.

shape as to suitably fit upon the body B, The hood is best constructed of sheet-metal. or other suitable cylindrical shell in'which the hood is to insert within it a sheet-metal that the heat of the are will first melt out the temporary lining cone] and then willed as usual of a metal shell filled with a 7o fined within,,-'-the body B.: Theencils or:

A 'Q tally, passiiigfreeiv -and adcjlustablylthrough];{- y B. and having is protected by a'circulation A of water through cooling pipes 11 d embeds5 invention, and maybe varied accordingto fuse downsuch portions of the lining h as approach too closely to the are, it being found that after a sufficient exposure to the heat of the arc, the lining, having fused back to approximately the outline a, resists further fusion. The hood is then ready for use.

' The hood is imperforate, so that there is no circulation of air or gases into or out of it. The expansion of gases may be provided for by venting through the feed-hole or around the carbonsa-wA feed-hole is shown atithrough which to introduce the material for treatment, and this hole may be either left open or only partially closed so as to enable the expansion or contraction of gases to take place through the vent thus formed.

Practical use of this furnace proves that when the refractory 1mm in the hood has" been fused back to a sufliclent distance from' the are, it becomes practically indestructible. This result is' believed to be due to the pres- 1 once beneath it and within the hollow ,of

the hood of a. mass or body of stagnant or quiescent gases which constitutes a thermic shield or non-heat-con lucting protector which s effective'to'interc pt so large a proportion of the heat rays that those which do penetrate to the lining are'inca'pable of fus -j This confined body of quiescent gas is believed to serve also as a reflector which is as effective for diiectingthe heat ing 1t.

rays downwardly as if the cover were solid. The stagnant air or gas in effect replaces a portion of the cover which constitutes the hollow or cavity in the hood, and its reverberatory effect appears to be equal to that of a revcrberatory furnace with a solid cover.

Although it is practieally'preferable to construct the hood E separately from the furnace body B, it must be understood that our invention is not limited to this mechanical construction. Any construction or ar- 'rangement whereby the furnace chamber is pro onged upward to a sufficient. height to mclose and retain a substantially inert gaseous shield of such thickness as to insure that the refractory walls inclosing this shield shall be protected from fusion, will answer the purpose. The height to which such upward extension of the-furnacechamber, or the interior of the hood if a separable hood is used, must be carried, will depend upon the nature of the refractory lining used elatively to the heat generating capacity of the furnace, and to the efficiency of the coolingmeans employed; that is to say, whether the exterior be coolcdso'lcly by radiation to the air, or by a circulation of -i:0l(l air against its exterior, or by a circulation of cooling liquid, all of which methods are well understood in the art;

Our invention is to be distinguished from those electric furnaces in which the furnace chamberis closed over by a roof orplate, the function of which is to transmit waste heat from the chamber to preheat the material to be treated in the furnace. The efl'ect of the body of inert air or gas in our furnace is to so effectually interceptthe heat rays that the lining of the furnace top or hood is effectually protected againstv fusion and no efi'ectiveheat passes through the non-conducting lining which confines this gaseous body. Thus our invention, instead ofutilizing heat which traverses the furnace top, aims to effectually prevent the transmission of heat through this top, and to this'enduses not onlythe non-conducting gaseous body, but also a lining which, constitutes as effective a non-conductor as possible.

\Ve claim as our 'invention:

1. A reverberatory electric furnace havlng a closed -top 'and non-conducting lining adapted to inclose and retain a-substantially inert gaseous body of sufiicientthickness to protect the lining beyond it from fusion, 2. A reverberatory-electrlc furnace comprisingelectrodes and a furnace chamber,

with a closedtopand a non-conducting liningghaving' an upwardly extending cavity of suflicient height to inclose and retain a substantially ,inert gaseous body of such thickness as: to protect the lining of said cavity fro'm fusion.

3. A rever'beratory electric furnace comp i'ising'a furnace chamber and electrodes, and a removable top consisting of a hollow hood covering said chamber having arefractory lining sufliciently remote from the source of heat to avoid fusion thereby, and adapted to inclose a substantially inertgaseous body serving as a heat shield.

4. A reverberatory electric furnace comprising a furnace chamber and electrodes,

the top of said chamber being extended upwardly, havinga refractory lining, and being iniperforate so'as to inclosc a substantially inert gaseous body, and wcing of such height that the refractory lining is protected by-said gaseous body from fusion.

Tn witness whereof, I have hereunto signed my,v name in the presence of two subscribing witnesses.

FRANZ VON KUGELGEN.

-Vitnesses:

F. You Brenna, J'No. M. ()TEY.

In I witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

' GEORGE O. SltlVAltD.

l/Vitnesses:

Geo. I. SnwAnn, J USTIN C; Warans.

iio 

